Question

Possible Duplicate:
UILongPressGestureRecognizer on UITableViewCell – double call

I am new to iPhone,

I am displaying Alert when Button is pressed long, but when i press button long my alert view gets called again.

Here is my code snippet,

- (IBAction)longPressDetected:(UIGestureRecognizer *)gestureRecognizer {

    //Gets text of Button.
    UIButton *btn = (UIButton *)[gestureRecognizer view];
    BtnText= [btn titleForState:UIControlStateNormal];
    NSLog(@"longPressDetected");

    UIAlertView* alert_view = [[UIAlertView alloc]
                               initWithTitle: @"Are you sure want to Delete ?" message:nil delegate: self 
                               cancelButtonTitle: @"Yes" otherButtonTitles: @"No", nil];
    [alert_view show];
    [alert_view release];
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{ 
    if (buttonIndex==0) {

        [self ReloadView];
         [alertView dismissWithClickedButtonIndex:0 animated:TRUE];
    }
    else{
        [alertView dismissWithClickedButtonIndex:1 animated:TRUE];
    }
}

Any help will be appreciated.

EDIT:

  -(void)viewWillAppear:(BOOL)animated
   {
         for(int i=0;i<10i++)
            {

                if(i!=0)
                {
                    if (i%4==0) 
                    {                    
                        ypos+=180;
                        xpos=30;
                    }
                    else
                    {
                        xpos+=200;
                    }
                }


                button = [UIButton buttonWithType:UIButtonTypeCustom];
                button.frame = CGRectMake(xpos, ypos, 120,130);
                [button setBackgroundImage:[UIImage imageNamed:@"ibook2.png"] forState:UIControlStateNormal];
                [button setTitle:[NSString stringWithFormat:@"%@", [Downloadedepubs objectAtIndex:i]] forState:UIControlStateNormal];
                [button addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];

                 LongPress = [[UILongPressGestureRecognizer alloc] init];
                [LongPress addTarget:self action:@selector(longPressDetected:)];
                 LongPress.delegate = (id<UIGestureRecognizerDelegate>)self;
                [button addGestureRecognizer:LongPress];
                [self.view addSubview:button];
                [LongPress release];

      } 

   }

Answer 1

UILongPressGestureRecognizer is a long event process. Please check the event state either it has started, completed etc.

- (IBAction)longPressDetected:(UIGestureRecognizer *)gestureRecognizer {        

    if (gestureRecognizer.state == UIGestureRecognizerStateBegan){

        NSLog(@"Long press began");

    } else if ( gestureRecognizer.state == UIGestureRecognizerStateRecognized ) {

            NSLog(@"Long press UIGestureRecognizerStateRecognized");
    }
    else if (gestureRecognizer.state == UIGestureRecognizerStateEnded) {

        NSLog(@"Long press Ended");
    }
    else {

        NSLog(@"Long press detected.");
    }       
}

I think, better to use the UIGestureRecognizerStateBegan state in your case.

Please modify your longPressDetected() as

 -(IBAction)longPressDetected:(UIGestureRecognizer *)gestureRecognizer {

   if (gestureRecognizer.state == UIGestureRecognizerStateBegan){

       UIButton *btn = (UIButton *)[gestureRecognizer view];
       BtnText= [btn titleForState:UIControlStateNormal];
       NSLog(@"longPressDetected");

      UIAlertView* alert_view = [[UIAlertView alloc] initWithTitle: @"Are you sure want to Delete ?" message:nil delegate: self cancelButtonTitle: @"Yes" otherButtonTitles: @"No", nil];
      [alert_view show];
      [alert_view release];
      alert_view = nil;

   }
 }

Please check all the below UIGestureRecognizerStates

    UIGestureRecognizerStatePossible,   // the recognizer has not yet recognized its gesture, but may be evaluating touch events. this is the default state

    UIGestureRecognizerStateBegan,      // the recognizer has received touches recognized as the gesture. the action method will be called at the next turn of the run loop
    UIGestureRecognizerStateChanged,    // the recognizer has received touches recognized as a change to the gesture. the action method will be called at the next turn of the run loop
    UIGestureRecognizerStateEnded,      // the recognizer has received touches recognized as the end of the gesture. the action method will be called at the next turn of the run loop and the recognizer will be reset to UIGestureRecognizerStatePossible
    UIGestureRecognizerStateCancelled,  // the recognizer has received touches resulting in the cancellation of the gesture. the action method will be called at the next turn of the run loop. the recognizer will be reset to UIGestureRecognizerStatePossible

    UIGestureRecognizerStateFailed,     // the recognizer has received a touch sequence that can not be recognized as the gesture. the action method will not be called and the recognizer will be reset to UIGestureRecognizerStatePossible

    // Discrete Gestures – gesture recognizers that recognize a discrete event but do not report changes (for example, a tap) do not transition through the Began and Changed states and can not fail or be cancelled
    UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded // the recognizer has received touches recognized as the gesture. the action method will be called at the next turn of the run loop and the recognizer will be reset to UIGestureRecognizerStatePossible